Adware is software that is freely available for download, but differs from freeware in that adware is ad-sponsored. In many cases adware can be a type of Internet application that runs while the user is online, providing a live feed of changing advertisements, versus built-in static or limited advertising. Adware is a close cousin of spyware as many adware programs collect information about the user to send back to advertisers for purposes of profiling for targeted ad-serving.

In the early days of the dot com boom advertisers overestimated the response consumers would have to aggressive online advertising, and many dot coms that relied on income from advertising sponsors went bust. In the height of the advertising fury, a few Internet Service Providers (ISPs) even offered free Internet service in return for using adware that ran banners and feeds across every page. When it became clear that people did not want to endure aggressive advertising, even to get something for free, the ISPs switched to pay services, dropping the adware interface.

A programmer might choose to create adware in order to collect advertising fees to offset the cost of keeping a program in active development. However, adware is generally viewed unfavorably among the Internet community, and many of today’s most popular spyware programs search and alert the user of installed adware. Adware is considered a security risk and it is generally recommended that one not install adware.

Despite this, there are many adware programs on the Internet, some of them bundled with other programs, installed without the user’s knowledge. Kazaa, a popular peer-to-peer program is adware, along with CometCursor, Bonzi Buddy and Gator to name a scant few. Many adware programs claim not to be spyware because the Terms of Use contracts that accompany the programs reveal in some fashion that information about the user might be collected and reported for advertising purposes.

Qualcomm’s Eudora is a popular email client with a unique software model. The trial version is fully functional but will revert to adware or crippleware if one does not pay for the software by the conclusion of the trial period. In the adware mode all features are enabled but one must accept advertisements. In the crippleware mode key features are disabled, but the software remains free and does not contain advertisements. Finally, one can pay for the software and get all features enabled without advertisements. Qualcomm claims the adware version does not collect profiling information.

To keep your computer safe, be sure to use a good spyware scanner in addition to a virus scanner. A few of the most popular scanners for adware are Ad-Aware by Lavasoft, Spyware Doctor by PC Tools, and SpySweeper by Webroot.